I was in a 5 year relationship with an IV user who also had HIV and HepC. He exposed me to a whole world i never knew existed of hard drugs and the wonderful feelings that accompany them. We moved in together and had a wonderful relationship. He was upfront about his condition right from the start, and I loved him enough to look past it. We were safe in every aspect of our sexual relationship. We never injected in the same room, I even had my "safe room" where only my paranoid self could use. We eventually both got on methadone, and throughout our relationship I did not contract his diseases.
Now, the only downside to this is that 2 years after we mutually ended our relationship, he passed away from pneumonia (the HIV lowered his immune system so badly it killed him), and now I have to live with this. It is hard not to think of the "what ifs". What if he stopped taking his meds after we broke up? What could I of done to help if we were still together? Did he start using again? The guilt I feel is unreal. I know he was an adult and made his own choices, but it still hurts knowing what he went through by himself.
So in short, yes I have dated an IV user and he was a wonderful man, but make sure they are upfront about their condition if they have one, and if they do, how far along they are in their illness. Iif you aren't an IV user already, the temptation is overwhelming and can defeat you rather quickly when you constantly see someone else injecting.